Spring applied vacuum released brake



Feb. 28, 1950 M. E. NlELsEN SPRING APPLIED VACUUM RELEASED BRAKE Filed Feb. l, 1947 l f INVENTOR AT Y Patented Feb. 28, 1950 SPRING APPLIED VACUUM BRAKE RELEASED Martin E. Nielsen, El Cerrito," oal'if. Application February 1, 1947, Serial N o. 725,866

1 Claim.

This invention relates to brakes, and more particularly to brakes for automotive vehicles, the principal object being to provide a braking mechanism that will function automatically upon the removal of a restraining means as will be described herein.

A further object of the invention is the provision of a mechanism that will automatically maintain the brakes of a parked car in the applied position.

A still further object of the invention is the provision of means for manually releasing the automatic feature of the device.

I attain these objects by the mechanism illustrated in the accompanying drawing, in which- Figure l is a schematic layout of a mechanical braking mechanism incorporating my improved features.

Figure 2 is a detail of the brake operating cylinder and valve in the brake applied position.

Referring to the drawing in detail, an automobile chassis is indi-cated fragmentarily at 3, with rear brake drums 4, and front brake drums 5. The brake drums 4, and 5, are equipped with the conventional internal expanding type of shoes operated by the levers 6, and l, respectively. The levers B, and "l, are connected in the usual manner to the cross shaft y3, by the double cranks Il, yand by pull rods IIJ, and II, and I2, and I3, respectively. Up to this point, the mechanism as described is symmetrical relative to the longitudinal center line of the vehicle.

The cross shaft Il, is operated by a crank I4, connected to the piston I5, of a vacuum cylinder I 5, by means of the piston rod Il, and a link I8. rihe cylinder is connected to a vacuum tank through a three-way valve I9, and a check lvalve 29. It Ican also be connected to the atmosphere at port 2i, on the valve I9. A further lconnection is made from the same end of the cylinder I6, to an emergency cylinder 22, the piston 23, of which is manually operated by means of the hand lever 24, and link 25, and piston rod 26. A check valve 2l, is interposed between' cylinders IIS, and 22. A vacuum pump, which may be driven by the automobile engine, is provided for the purpose of maintaining a vacuumin the tank while the engine is running.

The brake pedal 2-8, operates the valve I9, by means of a link 29, and in its normal position, as shown in Figure 1, connects the cylinder I6, with the vacuum tank. lIn the depressed position, as shown on Figure 2, the valve I9, connects the cylinder I, to the atmosphere through port 2 I.

In operation, a vacuum is maintained in the tank which causes the piston I5, to assume a position at the forward end of the cylinder IE, and thus hold the entire brake mechanism in the brake released position as shown on Figure 1. The brakes are applied by depressing the foot pedal 28, which operates the valve I9, closing the connection to the vacuum tank and allowing air to enter the cylinder I6, through the port 2I. Balancing of the air pressure on each side of the piston I5, allows the tension springs 30, to actuate the levers 6, and 1, and thus apply the brakes. Figure 2, illustrates the position of the piston I5, and the valve I 9, when the pedal 28, is depressed.

During normal running operation, the pull rods IIl, and II, and I2, and I3, are maintained in a state of tension by the atmospheric pressure acting on the back side of the piston I5, which pressure is sufficient to overcome the force exerted by the springs 30; however, when the pressure is opposed by admission of air to the front side of the piston I5, the springs 3U, urge the levers 6, and l, to assume the brake applied position as shown in phantom on Figure l.

When the car is brought to a standstill, and the engine stopped, the vacuum tank is no longer able to maintain the piston I5, in the forward position, and the brakes are applied by the tension exerted by springs 3U. In order to release the brakes when the vacuum tank is inoperative, the emergency cylinder 22, is utilized by operation of the hand lever 213. This draws the air from the forward end of the cylinder I 6, and serves to hold the brakes in the released position until the engine is started and the vacuum pump once more begins to function.

Valve 20, prevents any ingress of air to the cylinder IIB, from the vacuum tank, when the emergency cylinder is being used, and valve 21, forms a similar function by sealing the cylinder I6, against any leakage through cylinder 22, during normal running operation.

From the foregoing it will be apparent that I have devised a braking system that provides safety features not found on the conventional type of brake. If any part of the mechanism fails, as for instance the breaking of a pull rod or a shackle connection becoming detached, the brakes will automatically be applied and the vehicle brought to a stop. It will also be apparent that as the tank is unable to maintain a vacuum when the pump is inoperative, the brakes will always be automatically applied when the engine is stopped and the car is parked.

While I have disclosed -a preferred embodiment of my invention, it will be understood that modi- 3 cations may be made within the spirit and scope of the appended claim.

I claim:

In combination with plurality of brakes each having a brake drum and -a pair of brake shoes being normally set on the drum, with a brake operating mechanism comprising a vacuum brake cylinder having a piston adapted to slide therein; a v-acuumftank` connected Withsaid.l cylinderand adapted` to operate said piston; `means connecting said piston with the brake shoes; a valve between said cylinder and said vacuum tank adapted tor: connect said cylinder with the vacuum-tankv or with the atmosphere; said piston being adaptedl to actuate said brake shoes to release the brakes 15 2,318,798

4 when said cylinder is connected with the vacuum tank; an emergency cylinder connected with the iirst cylinder; and means for creating vacuum in the emergency cylinder.

MARTIN E. NIELSEN.

REFERENCES CITED l The following references are of record in the lezof thisipatent:

UNTTED STATES PATENTS Number Name Date 548,474 Snell Oct. 22, 1895 1,605,747 Magness Nov. 2, 1926 Piron May 11, 1943 

